Send Calendar meetings on someone's behalf

A few of our users used to be able to Send meeting requests on someone's behalf when using Exchange. This doesn't work with ZCS with Outlook 2003 or 2007. I checked the webmail version of the program to try to do it to see if it worked there and it didn't as well but in the HELP section of the webmail it shows that this is feature is supported.

Each user has full admin access to the other persons mailbox. They are able to send normal e-mails on behalf of the person but not calendar meeting requests. Is this a known issue or is this simply not supported in Zimbra at the moment and the help file is wrong?

I just tried this on our test server and it worked. We're using ZCS 6.0.5 on RHEL.

Let's say User A wants to send an invite on behalf of User B. To do this B would share his/her calendar (not mailbox) with A, with that A would use his/her ZWC to create a new appointment in B's calendar sending invites to other users. The invitees receive the message indicating that it's from A on behalf of B.